1. The Field of the Invention
This invention relates to novel, improved, particulate polymeric materials. A principle object of the invention is to provide novel, improved particulate polymeric materials which can be arranged in a predetermined three dimensional pattern, fused and cooled to provide three dimensional polymeric articles. Another object of the invention is to provide a novel, improved process for producing improved three dimensional polymeric articles.
2. The Prior Art
Particulate polymeric materials such as polymeric powders are known in the art and are used to produce three dimensional polymeric articles in known manners. Processes and apparatus suitable for providing polymeric articles by first fusing and then cooling three dimensional patterns or arrays of polymeric powders are disclosed and claimed in commonly assigned U.S. Pat. No. 4,475,477 issued to Morse et al and U.S. Pat. No. 4,480,581 issued to R. C. Simmonds Jr. et al and in commonly assigned U.S. patent application Ser. No. 452,964 filed Dec. 29, 1982 by R. C. Simmonds Jr. et al, now abandoned, and U.S. patent application Ser. No. 452,962 filed Dec. 29, 1982 by R. C. Simmonds et al, now U.S. Pat. No. 4,540,608. Additional details relating to processes or apparatus or articles involving polymeric powders can be found in commonly assigned U.S. patent application Ser. No. 452,963 filed Dec. 29, 1982 by R. C. Simmonds Jr. et al, now U.S. Pat. No. 4,528,710, and in U.S. patent application Ser. No. 557,453 filed Dec. 2, 1983 by R. Elliott et al, now abandoned, and in U.S. patent application Ser. No. 558,057 filed Dec. 5, 1983 by R. Elliott et al now U.S. Pat. No. 4,503,091, and in U.S. patent application Ser. No. 556,270 filed Nov. 30, 1983 by A. Gilbride et al, now U.S. Pat. No. 4,502,411, and in U.S. patent application Ser. No. 556,451 filed Nov. 30, 1983 by A. J. Morse et al, now U.S. Pat. No. 4,520,751. All of the above mentioned U.S. patents and applications are expressly incorporated here in their entirety by reference.
According to the teachings of the above patents and applications, three dimensional polymeric articles are produced by depositing or otherwise arranging a three dimensional pattern of a polymeric powder on the surface of a preferably movable receiving belt or web. The pattern of polymeric powder is then transported to a heating station where the powder is fused and the fused mass is then transported to a cooling station where another substrate may be pressed on or otherwise joined to the surface of the mass. At the cooling station, the fused, three dimensional polymeric article is lifted or otherwise removed from the receiving belt by suitable transfer means. Polymeric powders suitable for use in the processes and apparatus disclosed and claimed in the above mentioned U.S. patents and applications include polyolefins, polyesters, polyamides and polyurethanes among others.
In the above mentioned U.S. patents and applications, a release agent is applied to the receiving belt or surface carrying the pattern of polymeric powder. The release agent is primarily required in order to effectively prevent adhesion of the surface of the fused mass to the surface of the receiving belt. Additionally the release agent is required so that the three dimensional mass can be effectively removed from the belt surface usually near or above the Vicat temperature of the polymeric powder. While release agents perform an important function in the prior art processes and apparatus for producing polymeric articles comprising polymeric powders, the use of such release agents presents undesirable operational features. First, the application of the release agent to the belt is time consuming and waste can result if the release agent is not applied properly. Moreover, the release agent can stain the final polymeric article. Additionally removal of the release agent from the surface of the polymeric article is oftentimes required if the surface of the article is to be coated such as with paints or adhesives or the like. The invention is directed to the problems arising out of use of release agents in providing polymeric articles from polymeric powders and provides a novel, simple but especially effective solution for those problems.